Ball joint

ABSTRACT

The invention relates to a ball joint, especially a wheel guidance joint for motor vehicles. Said ball joint comprises a housing ( 1 ) with a cavity ( 2 ) that is open to at least one side. A bearing shell ( 3 ) that accommodates a ball ( 4 ) is inserted in said cavity. The bearing shell ( 3 ) can be displaced, together with the ball ( 4 ) that it receives, in the cavity ( 2 ) along an axis ( 6 ). A first shoulder ( 7 ) and a second shoulder ( 8 ) define end stops in the cavity ( 2 ) of the housing ( 1 ), a limited free trajectory ( 5 ) of the displaceable bearing shell ( 3 ) being defined between said two stops. The inventive joint is further characterized in that the bearing shell ( 3 ) is mounted in the cavity ( 2 ) under the effect of a gentle radial pretension. At least one compensating element ( 15 ) is arranged between the outer surface of the bearing shell ( 3 ) and the inner surface of the cavity ( 2 ).

[0001] The present invention pertains to a ball-and-socket joint according to the preamble of patent claim 1.

[0002] Such a ball-and-socket joint, as is known, e.g., from U.S. Pat. No. 6,042,294 or U.S. Pat. No. 6,010,272 and can be used as a wheel guide joint for motor vehicles, comprises a housing, which has a cavity that is open on at least one side. A bearing shell with a joint ball mounted therein is inserted into this cavity.

[0003] In solutions according to the documents cited, the bearing shell is displaceable together with the joint ball accommodated by it in the cavity along an axis coinciding with the axis of symmetry of the bearing shell, and a first collar and a second collar, between which a limited free path of the displaceable bearing shall is thus defined, form end stops in the cavity of the housing, so that the assembly unit comprising the bearing shell and the joint ball can be moved slidingly to and fro between the first collar and the second collar of the housing. Slide bearings have a clearance, which is called “bearing slackness,” between the bearing surfaces sliding on one another. This bearing slackness is the cause that the combination of a slide bearing with a ball-and-socket joint has been able to be solved only unsatisfactorily so far. The ball-and-socket joint embodiments according to U.S. Pat. No. 6,042,294 or U.S. Pat. No. 6,010,272 also fail to offer a satisfactory solution to this.

[0004] Another problem is that especially the ball-and-socket joints in the wheel carrier of a motor vehicle are subject to high thermal loads. These stem from adjacent components, such as the brakes, and have a lasting affect on the mounting characteristics. Even though heat protection shields are sometimes meaningful, they cannot permanently protect the ball-and-socket joints, so that there is a need for joints that have an approximately constant mounting characteristic despite extreme temperature changes. These difficulties in prior-art ball-and-socket joints increase with increasing outside temperature and are additionally intensified by the temperature effects on the components receiving the ball-and-socket joint in the motor vehicle.

[0005] The technical object of the present invention can be considered to be to provide a ball-and-socket joint that effectively compensates shape, position and location tolerances as well as deformations of the components of the ball-and-socket joint which are caused by thermal load or by the action of external forces.

[0006] This object is accomplished with the characterizing features of patent claim 1. Embodiments of the present invention are the subject of the subclaims.

[0007] A completely new approach is taken in the present invention. It is desirable and also achieved here by the embodiment according to the present invention that the bearing shell can move together with the joint ball mounted by it within the housing. Consequently, there is a sliding connection between the outer surface of the bearing shell and the inner surface of the cavity of the housing, in which the bearing shell is accommodated. This solution, which is known per se, is improved according to the present invention by the bearing shell being accommodated in the cavity of the housing under a slight radial pretension, i.e., by the bearing shell being correspondingly supported at the walls of the cavity. This can be imagined, e.g., such that at least one compensating element is arranged between the outer surface of the bearing shell and the inner surface of the cavity.

[0008] The bearing shell may be displaceable together with the joint ball accommodated by it in the cavity along an axis, and the location of the axis does not necessarily have to coincide with the axis of symmetry of the bearing shell. Rather, an inclination of the axis within the joint housing is also within the scope of the present invention.

[0009] Both shape and position tolerances of the ball-and-socket joint and deformations of the components of the ball-and-socket joint which are caused by thermal loads or by the action of external forces can be effectively compensated with such a ball-and-socket joint design. Moreover, a ball-and-socket joint was created that is free from clearance in the radial direction.

[0010] Thermal stresses and, to a lesser extent, even bending, e.g., the sagging of the wheel carrier as a consequence of lateral forces acting on the wheel carrier, can be compensated. The ball-and-socket joint, designed as a movable bearing, transmits radial forces and thus improves the lateral guiding of the wheel of the motor vehicle, which is of considerable advantage especially at the beginning of travel and during braking.

[0011] According to one embodiment of the present invention, the above-mentioned radial pretension can be generated by recessing at least one groove in the outer surface of the bearing shell and inserting a compensating element into each groove.

[0012] To generate the radial pretension as uniformly as possible, it is meaningful to provide at least two parallel grooves located at spaced locations from one another with compensating elements inserted in them.

[0013] The outer dimensions of the compensating element or the compensating elements should be slightly larger than the inner dimension of the cavity of the housing. For example, a slightly crowned outer dimension of each compensating element is particularly advantageous, and the compensating element should have at least a limited elasticity.

[0014] The housing of a ball-and-socket joint according to the present invention can be made open on one side or on both sides. In the case of a housing open on one side, it is possible to use the bottom of the housing as a second collar.

[0015] Furthermore, it is considered to be meaningful to provide, on a housing that is open on both sides, a first collar, which comprises, e.g., a part of the housing edge directed toward the inside of the joint, and a second collar, which may be designed as a radial flange area of a closing element.

[0016] Any component that is able to protect the sensitive inner parts of the bearing from contaminants or from the penetration of moisture may be used as a closing element. For example, sealing bellows made of rubber materials have been known.

[0017] Corresponding to a further suggestion, the closing element inserted into a mount of the housing may be fixed by the deformation of a material bead of the housing edge at the housing, which takes place during the closing of the ball-and-socket joint.

[0018] The closing element may have a one-part design, but it may also have a multipart design and comprise, e.g., a closing ring and a cover sealingly connected to same. It is recommended that at least one sealing element be used to improve the sealing between the closing ring and the cover. A round ring made of rubber shall be mentioned here only as an example of such a sealing element.

[0019] In further embodiments of the present invention, the joint ball may be connected detachably to a pivot. This offers the possibility of connection to components, which can be manufactured separately, in one ball pivot, which is especially useful if surface protection is necessary on only one of these components and nevertheless offers the possibility of a modular system, which makes it possible to manufacture the ball pivot according to the needs from standardized individual parts.

[0020] Moreover, the pivot may also be designed as a component of a wheel carrier of a motor vehicle. Due to this measure, i.e., the direct connection of the joint ball to a pivot made in one piece with the wheel carrier, additional attached parts and consequently mounting operations can be eliminated.

[0021] A special exemplary embodiment of the present invention will be explained in greater detail below with reference to the drawings.

[0022] In the drawings,

[0023]FIG. 1 shows a cross section of a detail of a ball-and-socket joint according to the present invention.

[0024] In the figure, a joint ball 4 is placed on a pivot 14 of a wheel carrier 18. The joint ball 4 is detachably connected to the pivot 14 by a screw connection 19.

[0025] With its spherical geometry, the joint ball 4 is accommodated in a bearing shell 3, which has an inner geometry complementary to the joint ball 4. In the example being shown, a cylindrical cavity 2, into which the bearing shell 3 is inserted in a slidingly movable manner, is present in a housing 1 of the ball-and-socket joint, which housing is open on both sides. When viewed in the direction of the axis 6, two circular grooves 16 are recessed at axially spaced locations from one another into the outer surface of the bearing shell. The grooves 16 accommodate a compensating element 15 each, which generates, relative to the axis 6, a radial pretension between the bearing shell 3 and the inner surface of the cavity 2. Tolerance compensation is thus achieved and the bearing shell is prevented, furthermore, from performing a rotary movement around the axis 6. The radial rigidity, i.e., the damping properties of this ball-and-socket joint, can be set highly accurately in the radial direction. It can also be determined from the figure that the outer circumference of the compensating element 15 is crowned here, and a ring-shaped cross section was therefore selected. This guarantees the absence of radial clearance, on the one hand, and, on the other hand, the easy axial mobility of the assembly unit comprising the joint ball 4 and the bearing shell 3 within the cavity 2.

[0026] The housing 1 has, furthermore, a first collar 7 as well as a second collar 8 on the opposite side. The distance between these collars is selected to be equal to the height of the bearing shell 3. Thus, a free path 5 is left, which makes possible the axial mobility of the assembly unit comprising the bearing shell 3 and the joint ball 4.

[0027] In the exemplary being shown, a part of the housing edge directed toward the inside of the joint is used as the first collar 7, and a radial flange area 20 of a closing element designated as a whole by 9 is used as the second collar 8. The closing element 9 is of a multipart design here for reasons of mounting. It comprises a closing ring 12 and a cover 12 forming a driving fit with the closing ring 11. For better sealing, a sealing element 13 was inserted between the cover 12 and the closing ring 11.

[0028] During the mounting of the ball-and-socket joint, the closing ring 11 is first inserted with a radially directed flange area 20 into a mounting groove 21 arranged on the inside of the housing. Deformation of a material bead 10 of the housing edge subsequently takes place during the closing of the housing, as a result of which the closing ring 11 is fixed.

[0029] A heat protection shield 17 protects the components of the ball-and-socket joint in the known manner from the harmful heat radiation of adjacent components. These are the brakes of the motor vehicle at the wheel carrier 18.

[0030] To optimize the sealing of the ball-and-socket joint against external effects, an elastic seal 23, whose outer elastic sealing surface 24 is supported against the heat protection shield of the ball-and-socket joint, is inserted into a ring area 22. The seal 23 is arranged on the pivot side, i.e., on the side of the first collar 7 at the joint housing, and the mounting may be performed by using a connection incorporated into the material or by a positive-locking or nonpositive connection. To improve the elasticity, the seal 23 was made of a rubber material, which has an insert 25 in this embodiment. The seal has, furthermore, a bead-like section 26.

[0031] List of Reference Numbers

[0032]1 housing

[0033]2 cavity

[0034]3 bearing shell

[0035]4 joint ball

[0036]5 free path

[0037]6 axis

[0038]7 first collar

[0039]8 second collar

[0040]9 closing element

[0041]10 material bead

[0042]11 closing ring

[0043]12 cover

[0044]13 sealing element

[0045]14 pivot

[0046]15 compensating element

[0047]16 groove

[0048]17 heat protection shield

[0049]18 wheel carrier

[0050]19 screw connection

[0051]20 flange area

[0052]21 mounting groove

[0053]22 ring area

[0054]23 seal

[0055]24 sealing surface

[0056]25 insert

[0057]26 bead-like section 

1. Ball-and-socket joint, especially wheel guide joint for motor vehicles with a said housing (1), in the said cavity (2) of which, which is open on at least one side, a said bearing shell (3) is inserted with a said joint ball (4) mounted therein, wherein the said bearing shell (3) forms a said assembly unit (3, 4) together with the said joint ball (4) accommodated therein, which said assembly unit is displaceable in the said cavity (2) along a said axis (6), and a said first collar (7) and a said second collar (8), between which a said limited free path (5) of the said displaceable assembly unit (3, 4) is defined, form end stops in the said cavity (2) of the said housing (1), characterized in that the said bearing shell (3) is accommodated in the said cavity (2) under a slight radial pretension and at least one said compensating element (15) is arranged between the said bearing shell (3) and the inner surface of the said cavity (2).
 2. Ball-and-socket joint in accordance with claim 1, characterized in that at least one said groove (16) is recessed in the outer surface of the said bearing shell (3) and a said compensating element (15), whose outer dimension is slightly larger than the inner dimension of the said cavity (2), is inserted into each groove.
 3. Ball-and-socket joint in accordance with one of the above claims, characterized in that on the said housing (1), which is open on both sides, the said first collar (7) is a part of the housing edge directed toward the inside of the joint, and the said second collar (8) is a said radial flange area (20) of a said closing element (9).
 4. Ball-and-socket joint in accordance with claim 3, characterized in that the said closing element (9) inserted into a said mount (21) of the said housing (1) is fixed by a said deformed material bead (10) after the mounting of the ball-and-socket joint.
 5. Ball-and-socket joint in accordance with claim 3 or 4, characterized in that the said closing element (9) has a multipart design and comprises a said closing ring (11) and a said cover (12) sealingly connected to same.
 6. Ball-and-socket joint in accordance with claim 5, characterized in that at least one said sealing element (13) is accommodated between the said closing ring (11) and the said cover (12).
 7. Ball-and-socket joint in accordance with one of the above claims, characterized in that the said joint ball (4) is detachably connected to a said pivot (14).
 8. Ball-and-socket joint in accordance with claim 7, characterized in that the said pivot (14) is part of a wheel carrier of a motor vehicle.
 9. Ball-and-socket joint in accordance with one of the above claims, characterized in that the ball-and-socket joint has a said heat protection shield (17) for shielding against adjacent components. 